Balls roll in four rows of raceways precision-ground on the LM rail and LM block and are circulated by ball cages and end plates incorporated in the LM block. A wide and highly rigid LM Guide that uses ball cages to achieve low noise, long-term maintenance-free operation and high speed. Wide, Low Center of Gravity THe Model SHW, which has a wide LM rail and a low center of gravity, is optimal for locations requiring space saving and large MC moment rigidity. 4-way Equal Load Each row of balls is placed at a contact angle of 45° so that the rated loads applied to the LM block are uniform in the four directions (radial, reverse radial and lateral directions), enabling the LM Guide to be used in all orientations and in extensive applications. Self-adjustment Capability The self-adjustment capability through front-to-front configuration of THK's unique circular-arc grooves (DF set) enables a mounting error to be absorbed even under a preload, thus to achieve highly accurate, smooth straight motion. Low Dust Generation Use of ball cages eliminates friction between balls and retains lubricant, thus achieving low dust generation.